Boom-angle indicator for cranes



March 18, 1930. E. H. LICHTENBERG OOM ANGLE INDICATOR FOR CRANES Filed Juhe 24, 1929 IVENTOR Zzchten be'fg.

ATTO RN EYS Patented Mar. 18, 1930 UNITED I STA -Es PATENT orrlce ERICH H. LIGHTENBERG, OF MILWAUKEE, WISCONSIN, ASSIGNOR T KOEHRING COM- PANY, OF MILWAUKEE, WISCONSIN, A CORPORATION BOOM-ANGLE mmca'ron ro'a onaims Application filed June 24,

The present invention deals with devices for indicating the working radius of a crane, and is a division in part of my co-pending application for patent, Serial No. 253,669,

filed February 11th, 1928.

It is always desirable to obtain the maximum capacity from a machine, and in cranes or the like structures, if this maximum capacity is exceeded, the crane will overturn, causing a delay and possibly resulting in damage to the machine and operator thereof.

An object of my invention therefore, is to construct a simple device which is located on the boom of a crane orlike structure, and in-.

dicates the working radius of the machine under varying working conditions.

In carrying out my invention, I make use of a pendulum suspended from the boom and actuated by gravity. The pendulum has indicia thereon, which indicate the working radius of the machine, both for different angular relations of the boom in respect to the body and for different inclinations of the body itself.

A further object of my invention is to provide means whereby the device may be adapted so as to correctly indicate the working radius of the machine for difierent' len ths of booms. oing more into detail, the pendulum comprises a body portion and an arm ex- 7 tending therefrom, the periphery of the body portion and arm taking an arcuate form. The pendulum is suspended or pivoted at the center of the are so thatrotation thereof within a circular casing or cover is possible without the pendulum striking-against the cover. indicia are carried on the periphery or arcuate portion of the pendulum and the cover is .30 formed with a sight opening whereby the operator may see the indicia as they are brought before the sight opening.

In order to use my novel device with different lengths of booms, I propose to supply 5 bands with different sets of indicia thereon which may be slipped over the pendulum .member, the correct band bein used according to the length-of boom emp oyed. t is also important to note that when the machine body is swung about, the centrifugal 1929. Serial No. 373,296.

action increases the working radius, but this same action will affect the pendulum so as to indicate this increase.

For a full and more complete understanding of my invention, reference may be had to the followingdescription and accompanying drawing, in which Figure 1 is a side elevation of a crane with my invention applied thereto, and showing in dotted lines the change in the working radius produced by an inclination of the body or a swinging of the body.

Figure 2 is a side view of my indicating device applied to a crane boom.

Figure 3 is an end view of the device shown in Figure 2 and has parts broken away to bring out the construction of the same.

Figure 4 is a perspective view of one of the interchangeable bands.

' Like reference characters designate corresponding parts throughout the several figures of the drawings.

Referring to the drawings, A desi nates the swing body of a portable crane, the traction support for thesame, C the boom, and D the hoisting cable, all of conventional construction and well known in the art.

The indicator comprises the casing or housing composed of the base plate 10 having opposite apertured extensions 11 through which fastening members 12 are passed, and a cover member 13 removably secured to the base plate by means of the center bolt 14. Preferably the meeting edges of the cover and base plate are toothed or serrated so as to positively interengage and define a definite adjustment. This casing is secured to the side of the boom at a convenient point near its pivot so as tobe within easy view of the operator standing upon the platform of the machine.

Within-the casing on the bolt 14 is swung the pendulum member 15 which carries a taillike extension 15' adapted to operate in relation to a window 16in the casing cover 13. Upon the peripheral surface of this member suitable indioia 17 are provided, calibrated in proper order and terms representing the working radius. This calibration is necessarily based upon the angleof the boom relalength. Thus, when a longer boom is used,

it is only necessary to remove the cover member and place the proper band over the pendulum member 15.

It will be apparent from the foregoing that as the boom is shifted upwardly or downwardly, the indicator member will shift in relation to the window 16, owing tothe tendency of the weight body to maintain its pendant position and by observing the indicia through the window the operator is always advised of the particular working radius.

When the machine is swung around, centrifugal force acts to extend the working radius but since this force obviously acts upon the pendulum or indicator member 15 to swing it around its support, a higher reading at the window 16 will be presented. Likewise, when the machine tips up, as shown in dotted lines in Figure -1, the reading changes upwardly, because the angle between the boom and the perpendicular line changes, causing the rotation of the indicator member.

In the preferred form of my invention, the

pendulum 15' will carry suitable? indicia thereon, to properly indicate the working radius of the boom length most commonly employed, and the extra bands will be provided to adapt the device for use with other lengths of booms.

Having thus described myinvention, what I claim as new and desire to secure by Letters Patent of the United States, is: Y

1. In combination, a boom hoist, means for adjusting the boom hoist, and indicator means carried by said boom hoist shiftable incident to adjustment of the hoist. V

2. In combination, a boom hoist, means for adjusting the boom hoist, indicator means carried by said boom hoist shiftable incident to adjustment of the hoist, and means to swingable body, a boom carried thereby and adjustable in respect thereto, and indicator,

means carried bythe boom, said means being adapted to indicate the working radius of the machine throughout the operation of the machine.

6. In a material handling machine, the combination, with a body and a boom carried thereby and adjustable in respect thereto, of a working radius indicator carried by the boom, said indicator comprising, a freely suspended member actuated by gravity and movable relative to a second member, and means for indicating the relative movement between the two members.

7. In combination, a boom hoist, means for adjusting the boom hoist, and a gravity actuated working radius indicator carried by said boom hoist.

8. In combination, aboom hoist, means for adjusting the boom hoist,"and' a gravity actuated working radius indicator carried by said boom hoist, said indicator comprisinga pendulum, indicia on the pendulum, and a memher having a sight opening therein forpermitting the operator to view the working radius indicated thereby.

9. In a working radiusindicator for cranes, the combination, with a member having indicia thereon, of means for replacing said in-' dicia thereby adapting said member to be used with booms of varying lengths.

In testimony whereof I aflix my signature.

ERIQH H. LICHTENBERG.

adapt the indicator means for hoists of various lengths. I

3. A material handling machine of the class described, comprising, in combination, a

, body, a boom-supported thereby and adjustable in respect t ereto, and indicator means carried by the boom, said means being shift-'- gblde incident to. changes ininclination of the o y.

4. A. material handling machineof the I class described, comprising, in combination, a

swingable body, a boom carried thereby, and

indicatormeans on the boom'for indicating the working conditions of the machine pre- .vailin during swingingof the body. v 5. material handling machine of the class described, comprising, incombinati'on, a 

